Abstract: The relationship between the natural frequency of roadbed soil and the soil compaction degree is the foundation for accurately establishing the relationship between the vibration signal of vibration roller and the compaction degree of soil and is the basis for effectively adjusting work parameters of vibratory roller to improve the compaction efficiency based on the real-time compaction condition of roadbed by online detecting vibration signal. Taken specific roadbed soil as study subjects, cylinder soil samples were made by homemade spiral compacting mechanism in this paper. Based on the modal analysis method and using INV306DF portable intelligent signal acquisition and processing analysis system, the natural frequency tests were done for different cylinder soil samples with different compaction degree. The function relation expression was obtained between natural frequency and compaction degree of roadbed soil. This study provides a reference for improving the intellectualized control system of vibratory roller.